But that is ok, I learned something new!
I don't know when the change came about, but I updated to the latest version 5.4.4599 and found that there is either a new file or a large change. The file in question is:
[Site Directory]/includes/Application.cfc
I run a custom banner page so I can have those randomly generated images that you see above. Read more to find out the details and the little addition to get your pages running again and not showing Access Restricted.